Self-adjusting mechanism for hydraulic wheel brakes



WS@ /d /5- July 16, 1946 A. G. TAYLOR 2,404,326

SELF-ADJUST'ING' MECHANISM FOR HYDRAULIC WHEEL BRAKES Filed July- 18, 1945 AHMUYGQOYQQTOLHIO" u \N\/ENTOf?-, @d 9m ATTY.

Patented July 16, 1946 TED s SEEE-ADJUSTING iviEcnAisusMfEoa I 1. A

uHYDRAULIC WHEEL BRAKES f .fArthurGeorge Taylor, Hadley; Barnet; England,

' assgnor of'one-half to F. J.'W,alkerr;Engineering Company Limited, Barnet, Englanma Brt- I-,ish .company Application July 1s, 1945,'serija1fNo. 605,727 'inoreatritain July 31;"71944I '.zfrhisinvention relatesto fhydraulicallyactuated wheelybrakestand isf particularly concerned with .thewheelbrakesfof'motor-cars. 1

Brake mechanisrr'i'sxmly."have` `a ilimitedgmoveimentfand as thezhr'ake,shoe'linings wear down .it sislfjnecessaryaat fintervalsu to adjust :the actuat- :ingtimechanismffwhich is oftenfamatter ofediilc ulty".avhereiithereare# several mechanisms, as with;thezbrakes-cf motor..cars, which:have to be balanced.V :Itwis known that-the manual adjustment of ',:brakefmechanisms isg'tedious and hence isrigofiten neglectedandv to ,-obviate, this there -have been-proposals? to fprovide e adegree ofF automatic adjustment in 'the ,actuating f mechanism. This mayv bey-more or less satisfactorily laccomplished `which ,will-.Vary the :length ofeach-,opeiating rod withzafdegfree of play which will avoid bindingof the rbrakes. The; problem -is-` more f -serious with hydraulically yoperated fbrakesaand automatic ad'- j-usi'mentcan Aonly be accomplishedv by providing Yadditional-fmeans-.Which -act asfvariablenretractive stops. Such additional Imeans complicate the rfmechanism-and as. they: cannot yheplaced 'at Ethe rpointfof maximum .movementrof shoest due tothe `"lfiydraulic "cylinder, there situated rthey` .can -only Y give a limited ldegreeoftl rough-adjustment.

. VVThe Fprincipal,object of `.thepresent invention -is-tomrovidean improved. automatic self -adjust- .ing mechanismk to .compensate for wearing .down of: .thebrakelinings oina; hydraulically. actuated .brakegwhich is. vof simple, efficient, construction t and capable:-of..givingnne :adjustmentwithout aecting the design .o1-,construction of the. brake meohanismeorl requiring... the fprovision fof.; additionalpar-ts.. `.A furtherobject of'the :invention is to so locategthe,,adjustingmeans thatthey are 1 .eileotive .at .the .points of .maximum t movement of .ithe .brakevshoes fon :morecertain .operation .with

amplemargin of play. to avoid., binding ,of the brake, shoes.

y .iALfIi'rtlrierc obj ectl of; the invention is .to ,provide such an, adjusting; meclfianisrn,'.Whizh.A is .fully selfcompensating.

. L'Iheaboye and further objectsoi theinvention will be E apparentfrom the, following description. According to the present invention, .the `orl each piston in a cylinder of a hydraulicallyactuated brakev mechanism moves axia1ly.ofan internal vvrigid member which is not .aifectedjhythe fluid f Apressure; and uan element within1 such piston wliicliv has .an extent, ofv free .movementaxially thereof isadapted .to engage with aline of abutmen'ts on' '-thefi1i'gid member; such that after a` `Alzgre:determineddegree ofY `excess movement of 'n the t .4 claims. (criss-79.5.). K1

' at one oreach end ofl which a series offconf;

Introd: operated'. :hralre/` mechanisms by kmeans piston; the extent-01E` retractive movement thereof is-limitedzf f i yThe rigid member which `.is-preferabl-y y located concentricawithi the pistol-Vork pistons in A. a cylinder,` conveniently takes .fthelform Vof a ster-n1,A or rod l20 :scribed A=,rwithreference to the faccompanying drawingcwhich is; given-:asa non-limitatvefex- "ample andfinwhich: i '.Eigure...:11-. isahalfsect-ionedfside :elevationI -of the-cylinder of far hyd-raulically joperated brake au with onefoffi-tsspistonsffandtheautomaticadjustment means-f associated therewith vshown inqfsecr tion; i f

, .fEigurex 2*:-is raflview similar to -Figurerl- .oft the A,same mechanism I but -,incorporating means for ,f dimtiingr. the `degree @of self-compensatory. imove- .ment,y. Fgures and 4 show end and sidesecton views respectively .of the elements .t which ,engager the `toothed,orrack rod,

Figure 5 is another view ,toEigure- -1 ,.showng.- anf alternative. form ,c of. :automaticadt ,jusltmenti means, Y

.Figure 6.f isaI sectiontaken on` theline ,oi Eigure 5.1ooking in thedirection of the arrows,

,.,Fig-ureljs a. plan view. on. ,amenlarged scale lookingdownon the ypistonseen in Figure 5*. i

'Beferringnow to tnesaidpdrawing.throughout which identicalpalts bear; likereference numertvalsQand infparticular toligurel thereof, Whois a Y cylinder ofl` normal; design ot .a hydraulically ,ac-

tuatedbrake mechanismV which is carriedJcyJaJ xed party and has1 a centrallyiocated orifice through which iluidlgflowsl in and out and by its pressure moves in opposite directions a pair of pistonstherebyto rock Y.at least, two brake shoes whihare retractedbya Sprnain thenormal -manne13r ,In the embodiment illustrated each piston is formed .of two parts 1.1,] [2.0i whichrthe latter, partially telescopes into the former. It ,form

PATE-N1" om@ v ting said engagement means to said ahnt--v ments in one direction only.

2. In a hydraulic brake, a cylinder,` two opposed pistons'in said cylinder, each piston havinga central axial bore, a free rod having its ends located loosely in said bores in said pistons, means for limiting the extent of free movement of said rod, a

series of abutments at each end of said rod, means Y i for engaging said abutments to pass the same in only one direction, and means within each of said pistons to contain said engaging means for lime ited axial movement.

3. In a hydraulicb'rake,v a cylinder, at least one Y piston located in said cylinder and having a central axial bore therein; a rod terminating in buttress teeth loose in said bore in said piston, a pair of elements embracing and resiliently urged to engage. said teeth, and means'in said cylinder to contain and permit limited axial movement o! said pair of elements. Y

4. In a hydraulic brake, a cylinder, at least on l piston located in said cylinder and having a central axial bore thereima rod terminating in a plurality of abutments located loose in said bore in said piston, a pair of elements embracing and re' Y 1 siliently urged to engage saidabutments, means permitting said elements to pass said abutments in one direction only, means in said cylinder to contain and'permit limited axial movement of said pair of elements, and means for limiting the Y 

